[PATCH AUTOSEL 6.11 44/76] media: videobuf2-core: clear memory related fields in __vb2_plane_dmabuf_put()

[PATCH AUTOSEL 6.11 44/76] media: videobuf2-core: clear memory related fields in __vb2_plane_dmabuf_put()

[Sasha Levin]

From: Yunke Cao <yunkec@chromium.org>

[ Upstream commit 6a9c97ab6b7e85697e0b74e86062192a5ffffd99 ]

Clear vb2_plane's memory related fields in __vb2_plane_dmabuf_put(),
including bytesused, length, fd and data_offset.

Remove the duplicated code in __prepare_dmabuf().

Signed-off-by: Yunke Cao <yunkec@chromium.org>
Acked-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/common/videobuf2/videobuf2-core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 0217392fcc0d9..4d232b08f9505 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -311,6 +311,10 @@ static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb, struct vb2_plane *p)
 	p->mem_priv = NULL;
 	p->dbuf = NULL;
 	p->dbuf_mapped = 0;
+	p->bytesused = 0;
+	p->length = 0;
+	p->m.fd = 0;
+	p->data_offset = 0;
 }
 
 /*
@@ -1420,10 +1424,6 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
 
 		/* Release previously acquired memory if present */
 		__vb2_plane_dmabuf_put(vb, &vb->planes[plane]);
-		vb->planes[plane].bytesused = 0;
-		vb->planes[plane].length = 0;
-		vb->planes[plane].m.fd = 0;
-		vb->planes[plane].data_offset = 0;
 
 		/* Acquire each plane's memory */
 		mem_priv = call_ptr_memop(attach_dmabuf,
-- 
2.43.0

[PATCH AUTOSEL 6.11 72/76] drm/amdgpu: nuke the VM PD/PT shadow handling

[Sasha Levin]

From: Christian König <christian.koenig@amd.com>

[ Upstream commit 7181faaa4703705939580abffaf9cb5d6b50dbb7 ]

This was only used as workaround for recovering the page tables after
VRAM was lost and is no longer necessary after the function
amdgpu_vm_bo_reset_state_machine() started to do the same.

Compute never used shadows either, so the only proplematic case left is
SVM and that is most likely not recoverable in any way when VRAM is
lost.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  4 -
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c  | 87 +--------------------
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c  | 67 +---------------
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.h  | 21 -----
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c      | 17 ----
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c   | 56 +------------
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c | 19 +----
 7 files changed, 6 insertions(+), 265 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 137a88b8de453..a1b2bf3db55b8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1091,10 +1091,6 @@ struct amdgpu_device {
 
 	struct amdgpu_virt	virt;
 
-	/* link all shadow bo */
-	struct list_head                shadow_list;
-	struct mutex                    shadow_list_lock;
-
 	/* record hw reset is performed */
 	bool has_hw_reset;
 	u8				reset_magic[AMDGPU_RESET_MAGIC_NUM];
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index bcacf2e35eba0..dfd468729d52b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4073,9 +4073,6 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	spin_lock_init(&adev->mm_stats.lock);
 	spin_lock_init(&adev->wb.lock);
 
-	INIT_LIST_HEAD(&adev->shadow_list);
-	mutex_init(&adev->shadow_list_lock);
-
 	INIT_LIST_HEAD(&adev->reset_list);
 
 	INIT_LIST_HEAD(&adev->ras_list);
@@ -4980,80 +4977,6 @@ static int amdgpu_device_ip_post_soft_reset(struct amdgpu_device *adev)
 	return 0;
 }
 
-/**
- * amdgpu_device_recover_vram - Recover some VRAM contents
- *
- * @adev: amdgpu_device pointer
- *
- * Restores the contents of VRAM buffers from the shadows in GTT.  Used to
- * restore things like GPUVM page tables after a GPU reset where
- * the contents of VRAM might be lost.
- *
- * Returns:
- * 0 on success, negative error code on failure.
- */
-static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
-{
-	struct dma_fence *fence = NULL, *next = NULL;
-	struct amdgpu_bo *shadow;
-	struct amdgpu_bo_vm *vmbo;
-	long r = 1, tmo;
-
-	if (amdgpu_sriov_runtime(adev))
-		tmo = msecs_to_jiffies(8000);
-	else
-		tmo = msecs_to_jiffies(100);
-
-	dev_info(adev->dev, "recover vram bo from shadow start\n");
-	mutex_lock(&adev->shadow_list_lock);
-	list_for_each_entry(vmbo, &adev->shadow_list, shadow_list) {
-		/* If vm is compute context or adev is APU, shadow will be NULL */
-		if (!vmbo->shadow)
-			continue;
-		shadow = vmbo->shadow;
-
-		/* No need to recover an evicted BO */
-		if (!shadow->tbo.resource ||
-		    shadow->tbo.resource->mem_type != TTM_PL_TT ||
-		    shadow->tbo.resource->start == AMDGPU_BO_INVALID_OFFSET ||
-		    shadow->parent->tbo.resource->mem_type != TTM_PL_VRAM)
-			continue;
-
-		r = amdgpu_bo_restore_shadow(shadow, &next);
-		if (r)
-			break;
-
-		if (fence) {
-			tmo = dma_fence_wait_timeout(fence, false, tmo);
-			dma_fence_put(fence);
-			fence = next;
-			if (tmo == 0) {
-				r = -ETIMEDOUT;
-				break;
-			} else if (tmo < 0) {
-				r = tmo;
-				break;
-			}
-		} else {
-			fence = next;
-		}
-	}
-	mutex_unlock(&adev->shadow_list_lock);
-
-	if (fence)
-		tmo = dma_fence_wait_timeout(fence, false, tmo);
-	dma_fence_put(fence);
-
-	if (r < 0 || tmo <= 0) {
-		dev_err(adev->dev, "recover vram bo from shadow failed, r is %ld, tmo is %ld\n", r, tmo);
-		return -EIO;
-	}
-
-	dev_info(adev->dev, "recover vram bo from shadow done\n");
-	return 0;
-}
-
-
 /**
  * amdgpu_device_reset_sriov - reset ASIC for SR-IOV vf
  *
@@ -5116,12 +5039,8 @@ static int amdgpu_device_reset_sriov(struct amdgpu_device *adev,
 	if (r)
 		return r;
 
-	if (adev->virt.gim_feature & AMDGIM_FEATURE_GIM_FLR_VRAMLOST) {
+	if (adev->virt.gim_feature & AMDGIM_FEATURE_GIM_FLR_VRAMLOST)
 		amdgpu_inc_vram_lost(adev);
-		r = amdgpu_device_recover_vram(adev);
-	}
-	if (r)
-		return r;
 
 	/* need to be called during full access so we can't do it later like
 	 * bare-metal does.
@@ -5541,9 +5460,7 @@ int amdgpu_do_asic_reset(struct list_head *device_list_handle,
 			}
 		}
 
-		if (!r)
-			r = amdgpu_device_recover_vram(tmp_adev);
-		else
+		if (r)
 			tmp_adev->asic_reset_res = r;
 	}
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index e32161f6b67a3..a987f671b1d53 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -77,24 +77,6 @@ static void amdgpu_bo_user_destroy(struct ttm_buffer_object *tbo)
 	amdgpu_bo_destroy(tbo);
 }
 
-static void amdgpu_bo_vm_destroy(struct ttm_buffer_object *tbo)
-{
-	struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
-	struct amdgpu_bo *shadow_bo = ttm_to_amdgpu_bo(tbo), *bo;
-	struct amdgpu_bo_vm *vmbo;
-
-	bo = shadow_bo->parent;
-	vmbo = to_amdgpu_bo_vm(bo);
-	/* in case amdgpu_device_recover_vram got NULL of bo->parent */
-	if (!list_empty(&vmbo->shadow_list)) {
-		mutex_lock(&adev->shadow_list_lock);
-		list_del_init(&vmbo->shadow_list);
-		mutex_unlock(&adev->shadow_list_lock);
-	}
-
-	amdgpu_bo_destroy(tbo);
-}
-
 /**
  * amdgpu_bo_is_amdgpu_bo - check if the buffer object is an &amdgpu_bo
  * @bo: buffer object to be checked
@@ -108,8 +90,7 @@ static void amdgpu_bo_vm_destroy(struct ttm_buffer_object *tbo)
 bool amdgpu_bo_is_amdgpu_bo(struct ttm_buffer_object *bo)
 {
 	if (bo->destroy == &amdgpu_bo_destroy ||
-	    bo->destroy == &amdgpu_bo_user_destroy ||
-	    bo->destroy == &amdgpu_bo_vm_destroy)
+	    bo->destroy == &amdgpu_bo_user_destroy)
 		return true;
 
 	return false;
@@ -722,52 +703,6 @@ int amdgpu_bo_create_vm(struct amdgpu_device *adev,
 	return r;
 }
 
-/**
- * amdgpu_bo_add_to_shadow_list - add a BO to the shadow list
- *
- * @vmbo: BO that will be inserted into the shadow list
- *
- * Insert a BO to the shadow list.
- */
-void amdgpu_bo_add_to_shadow_list(struct amdgpu_bo_vm *vmbo)
-{
-	struct amdgpu_device *adev = amdgpu_ttm_adev(vmbo->bo.tbo.bdev);
-
-	mutex_lock(&adev->shadow_list_lock);
-	list_add_tail(&vmbo->shadow_list, &adev->shadow_list);
-	vmbo->shadow->parent = amdgpu_bo_ref(&vmbo->bo);
-	vmbo->shadow->tbo.destroy = &amdgpu_bo_vm_destroy;
-	mutex_unlock(&adev->shadow_list_lock);
-}
-
-/**
- * amdgpu_bo_restore_shadow - restore an &amdgpu_bo shadow
- *
- * @shadow: &amdgpu_bo shadow to be restored
- * @fence: dma_fence associated with the operation
- *
- * Copies a buffer object's shadow content back to the object.
- * This is used for recovering a buffer from its shadow in case of a gpu
- * reset where vram context may be lost.
- *
- * Returns:
- * 0 for success or a negative error code on failure.
- */
-int amdgpu_bo_restore_shadow(struct amdgpu_bo *shadow, struct dma_fence **fence)
-
-{
-	struct amdgpu_device *adev = amdgpu_ttm_adev(shadow->tbo.bdev);
-	struct amdgpu_ring *ring = adev->mman.buffer_funcs_ring;
-	uint64_t shadow_addr, parent_addr;
-
-	shadow_addr = amdgpu_bo_gpu_offset(shadow);
-	parent_addr = amdgpu_bo_gpu_offset(shadow->parent);
-
-	return amdgpu_copy_buffer(ring, shadow_addr, parent_addr,
-				  amdgpu_bo_size(shadow), NULL, fence,
-				  true, false, 0);
-}
-
 /**
  * amdgpu_bo_kmap - map an &amdgpu_bo buffer object
  * @bo: &amdgpu_bo buffer object to be mapped
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
index bc42ccbde659a..a4fa1f296daec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
@@ -130,8 +130,6 @@ struct amdgpu_bo_user {
 
 struct amdgpu_bo_vm {
 	struct amdgpu_bo		bo;
-	struct amdgpu_bo		*shadow;
-	struct list_head		shadow_list;
 	struct amdgpu_vm_bo_base        entries[];
 };
 
@@ -269,22 +267,6 @@ static inline bool amdgpu_bo_encrypted(struct amdgpu_bo *bo)
 	return bo->flags & AMDGPU_GEM_CREATE_ENCRYPTED;
 }
 
-/**
- * amdgpu_bo_shadowed - check if the BO is shadowed
- *
- * @bo: BO to be tested.
- *
- * Returns:
- * NULL if not shadowed or else return a BO pointer.
- */
-static inline struct amdgpu_bo *amdgpu_bo_shadowed(struct amdgpu_bo *bo)
-{
-	if (bo->tbo.type == ttm_bo_type_kernel)
-		return to_amdgpu_bo_vm(bo)->shadow;
-
-	return NULL;
-}
-
 bool amdgpu_bo_is_amdgpu_bo(struct ttm_buffer_object *bo);
 void amdgpu_bo_placement_from_domain(struct amdgpu_bo *abo, u32 domain);
 
@@ -343,9 +325,6 @@ u64 amdgpu_bo_gpu_offset(struct amdgpu_bo *bo);
 u64 amdgpu_bo_gpu_offset_no_check(struct amdgpu_bo *bo);
 void amdgpu_bo_get_memory(struct amdgpu_bo *bo,
 			  struct amdgpu_mem_stats *stats);
-void amdgpu_bo_add_to_shadow_list(struct amdgpu_bo_vm *vmbo);
-int amdgpu_bo_restore_shadow(struct amdgpu_bo *shadow,
-			     struct dma_fence **fence);
 uint32_t amdgpu_bo_get_preferred_domain(struct amdgpu_device *adev,
 					    uint32_t domain);
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index a060c28f0877c..8cda1d02dade3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -465,7 +465,6 @@ int amdgpu_vm_validate(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 {
 	uint64_t new_vm_generation = amdgpu_vm_generation(adev, vm);
 	struct amdgpu_vm_bo_base *bo_base;
-	struct amdgpu_bo *shadow;
 	struct amdgpu_bo *bo;
 	int r;
 
@@ -486,16 +485,10 @@ int amdgpu_vm_validate(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 		spin_unlock(&vm->status_lock);
 
 		bo = bo_base->bo;
-		shadow = amdgpu_bo_shadowed(bo);
 
 		r = validate(param, bo);
 		if (r)
 			return r;
-		if (shadow) {
-			r = validate(param, shadow);
-			if (r)
-				return r;
-		}
 
 		if (bo->tbo.type != ttm_bo_type_kernel) {
 			amdgpu_vm_bo_moved(bo_base);
@@ -2123,10 +2116,6 @@ void amdgpu_vm_bo_invalidate(struct amdgpu_device *adev,
 {
 	struct amdgpu_vm_bo_base *bo_base;
 
-	/* shadow bo doesn't have bo base, its validation needs its parent */
-	if (bo->parent && (amdgpu_bo_shadowed(bo->parent) == bo))
-		bo = bo->parent;
-
 	for (bo_base = bo->vm_bo; bo_base; bo_base = bo_base->next) {
 		struct amdgpu_vm *vm = bo_base->vm;
 
@@ -2454,7 +2443,6 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	root_bo = amdgpu_bo_ref(&root->bo);
 	r = amdgpu_bo_reserve(root_bo, true);
 	if (r) {
-		amdgpu_bo_unref(&root->shadow);
 		amdgpu_bo_unref(&root_bo);
 		goto error_free_delayed;
 	}
@@ -2546,11 +2534,6 @@ int amdgpu_vm_make_compute(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 	vm->last_update = dma_fence_get_stub();
 	vm->is_compute_context = true;
 
-	/* Free the shadow bo for compute VM */
-	amdgpu_bo_unref(&to_amdgpu_bo_vm(vm->root.bo)->shadow);
-
-	goto unreserve_bo;
-
 unreserve_bo:
 	amdgpu_bo_unreserve(vm->root.bo);
 	return r;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
index e39d6e7643bfb..c8e0b8cfd3363 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
@@ -383,14 +383,6 @@ int amdgpu_vm_pt_clear(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	if (r)
 		return r;
 
-	if (vmbo->shadow) {
-		struct amdgpu_bo *shadow = vmbo->shadow;
-
-		r = ttm_bo_validate(&shadow->tbo, &shadow->placement, &ctx);
-		if (r)
-			return r;
-	}
-
 	if (!drm_dev_enter(adev_to_drm(adev), &idx))
 		return -ENODEV;
 
@@ -448,10 +440,7 @@ int amdgpu_vm_pt_create(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 			int32_t xcp_id)
 {
 	struct amdgpu_bo_param bp;
-	struct amdgpu_bo *bo;
-	struct dma_resv *resv;
 	unsigned int num_entries;
-	int r;
 
 	memset(&bp, 0, sizeof(bp));
 
@@ -484,42 +473,7 @@ int amdgpu_vm_pt_create(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	if (vm->root.bo)
 		bp.resv = vm->root.bo->tbo.base.resv;
 
-	r = amdgpu_bo_create_vm(adev, &bp, vmbo);
-	if (r)
-		return r;
-
-	bo = &(*vmbo)->bo;
-	if (vm->is_compute_context || (adev->flags & AMD_IS_APU)) {
-		(*vmbo)->shadow = NULL;
-		return 0;
-	}
-
-	if (!bp.resv)
-		WARN_ON(dma_resv_lock(bo->tbo.base.resv,
-				      NULL));
-	resv = bp.resv;
-	memset(&bp, 0, sizeof(bp));
-	bp.size = amdgpu_vm_pt_size(adev, level);
-	bp.domain = AMDGPU_GEM_DOMAIN_GTT;
-	bp.flags = AMDGPU_GEM_CREATE_CPU_GTT_USWC;
-	bp.type = ttm_bo_type_kernel;
-	bp.resv = bo->tbo.base.resv;
-	bp.bo_ptr_size = sizeof(struct amdgpu_bo);
-	bp.xcp_id_plus1 = xcp_id + 1;
-
-	r = amdgpu_bo_create(adev, &bp, &(*vmbo)->shadow);
-
-	if (!resv)
-		dma_resv_unlock(bo->tbo.base.resv);
-
-	if (r) {
-		amdgpu_bo_unref(&bo);
-		return r;
-	}
-
-	amdgpu_bo_add_to_shadow_list(*vmbo);
-
-	return 0;
+	return amdgpu_bo_create_vm(adev, &bp, vmbo);
 }
 
 /**
@@ -569,7 +523,6 @@ static int amdgpu_vm_pt_alloc(struct amdgpu_device *adev,
 	return 0;
 
 error_free_pt:
-	amdgpu_bo_unref(&pt->shadow);
 	amdgpu_bo_unref(&pt_bo);
 	return r;
 }
@@ -581,17 +534,10 @@ static int amdgpu_vm_pt_alloc(struct amdgpu_device *adev,
  */
 static void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry)
 {
-	struct amdgpu_bo *shadow;
-
 	if (!entry->bo)
 		return;
 
 	entry->bo->vm_bo = NULL;
-	shadow = amdgpu_bo_shadowed(entry->bo);
-	if (shadow) {
-		ttm_bo_set_bulk_move(&shadow->tbo, NULL);
-		amdgpu_bo_unref(&shadow);
-	}
 	ttm_bo_set_bulk_move(&entry->bo->tbo, NULL);
 
 	spin_lock(&entry->vm->status_lock);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
index 9b748d7058b5c..390432a22ddd5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
@@ -35,16 +35,7 @@
  */
 static int amdgpu_vm_sdma_map_table(struct amdgpu_bo_vm *table)
 {
-	int r;
-
-	r = amdgpu_ttm_alloc_gart(&table->bo.tbo);
-	if (r)
-		return r;
-
-	if (table->shadow)
-		r = amdgpu_ttm_alloc_gart(&table->shadow->tbo);
-
-	return r;
+	return amdgpu_ttm_alloc_gart(&table->bo.tbo);
 }
 
 /* Allocate a new job for @count PTE updates */
@@ -273,17 +264,13 @@ static int amdgpu_vm_sdma_update(struct amdgpu_vm_update_params *p,
 
 		if (!p->pages_addr) {
 			/* set page commands needed */
-			if (vmbo->shadow)
-				amdgpu_vm_sdma_set_ptes(p, vmbo->shadow, pe, addr,
-							count, incr, flags);
 			amdgpu_vm_sdma_set_ptes(p, bo, pe, addr, count,
 						incr, flags);
 			return 0;
 		}
 
 		/* copy commands needed */
-		ndw -= p->adev->vm_manager.vm_pte_funcs->copy_pte_num_dw *
-			(vmbo->shadow ? 2 : 1);
+		ndw -= p->adev->vm_manager.vm_pte_funcs->copy_pte_num_dw;
 
 		/* for padding */
 		ndw -= 7;
@@ -298,8 +285,6 @@ static int amdgpu_vm_sdma_update(struct amdgpu_vm_update_params *p,
 			pte[i] |= flags;
 		}
 
-		if (vmbo->shadow)
-			amdgpu_vm_sdma_copy_ptes(p, vmbo->shadow, pe, nptes);
 		amdgpu_vm_sdma_copy_ptes(p, bo, pe, nptes);
 
 		pe += nptes * 8;
-- 
2.43.0

Re: [PATCH AUTOSEL 6.11 72/76] drm/amdgpu: nuke the VM PD/PT shadow handling

[Christian König]

Hi Sasha,

Am 04.10.24 um 20:17 schrieb Sasha Levin:
> From: Christian König <christian.koenig@amd.com>
>
> [ Upstream commit 7181faaa4703705939580abffaf9cb5d6b50dbb7 ]
>
> This was only used as workaround for recovering the page tables after
> VRAM was lost and is no longer necessary after the function
> amdgpu_vm_bo_reset_state_machine() started to do the same.
>
> Compute never used shadows either, so the only proplematic case left is
> SVM and that is most likely not recoverable in any way when VRAM is
> lost.

why is that backported to older kernels? It's basically just removing an 
old and now unused feature.

Lijo pointed out a related bug fixed by removing the feature, but that 
only happens extremely rarely and in my view doesn't really justify a 
backport.

Regards,
Christian.

>
> Signed-off-by: Christian König <christian.koenig@amd.com>
> Acked-by: Lijo Lazar <lijo.lazar@amd.com>
> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  4 -
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c  | 87 +--------------------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c  | 67 +---------------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.h  | 21 -----
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c      | 17 ----
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c   | 56 +------------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c | 19 +----
>   7 files changed, 6 insertions(+), 265 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 137a88b8de453..a1b2bf3db55b8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -1091,10 +1091,6 @@ struct amdgpu_device {
>   
>   	struct amdgpu_virt	virt;
>   
> -	/* link all shadow bo */
> -	struct list_head                shadow_list;
> -	struct mutex                    shadow_list_lock;
> -
>   	/* record hw reset is performed */
>   	bool has_hw_reset;
>   	u8				reset_magic[AMDGPU_RESET_MAGIC_NUM];
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index bcacf2e35eba0..dfd468729d52b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -4073,9 +4073,6 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>   	spin_lock_init(&adev->mm_stats.lock);
>   	spin_lock_init(&adev->wb.lock);
>   
> -	INIT_LIST_HEAD(&adev->shadow_list);
> -	mutex_init(&adev->shadow_list_lock);
> -
>   	INIT_LIST_HEAD(&adev->reset_list);
>   
>   	INIT_LIST_HEAD(&adev->ras_list);
> @@ -4980,80 +4977,6 @@ static int amdgpu_device_ip_post_soft_reset(struct amdgpu_device *adev)
>   	return 0;
>   }
>   
> -/**
> - * amdgpu_device_recover_vram - Recover some VRAM contents
> - *
> - * @adev: amdgpu_device pointer
> - *
> - * Restores the contents of VRAM buffers from the shadows in GTT.  Used to
> - * restore things like GPUVM page tables after a GPU reset where
> - * the contents of VRAM might be lost.
> - *
> - * Returns:
> - * 0 on success, negative error code on failure.
> - */
> -static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
> -{
> -	struct dma_fence *fence = NULL, *next = NULL;
> -	struct amdgpu_bo *shadow;
> -	struct amdgpu_bo_vm *vmbo;
> -	long r = 1, tmo;
> -
> -	if (amdgpu_sriov_runtime(adev))
> -		tmo = msecs_to_jiffies(8000);
> -	else
> -		tmo = msecs_to_jiffies(100);
> -
> -	dev_info(adev->dev, "recover vram bo from shadow start\n");
> -	mutex_lock(&adev->shadow_list_lock);
> -	list_for_each_entry(vmbo, &adev->shadow_list, shadow_list) {
> -		/* If vm is compute context or adev is APU, shadow will be NULL */
> -		if (!vmbo->shadow)
> -			continue;
> -		shadow = vmbo->shadow;
> -
> -		/* No need to recover an evicted BO */
> -		if (!shadow->tbo.resource ||
> -		    shadow->tbo.resource->mem_type != TTM_PL_TT ||
> -		    shadow->tbo.resource->start == AMDGPU_BO_INVALID_OFFSET ||
> -		    shadow->parent->tbo.resource->mem_type != TTM_PL_VRAM)
> -			continue;
> -
> -		r = amdgpu_bo_restore_shadow(shadow, &next);
> -		if (r)
> -			break;
> -
> -		if (fence) {
> -			tmo = dma_fence_wait_timeout(fence, false, tmo);
> -			dma_fence_put(fence);
> -			fence = next;
> -			if (tmo == 0) {
> -				r = -ETIMEDOUT;
> -				break;
> -			} else if (tmo < 0) {
> -				r = tmo;
> -				break;
> -			}
> -		} else {
> -			fence = next;
> -		}
> -	}
> -	mutex_unlock(&adev->shadow_list_lock);
> -
> -	if (fence)
> -		tmo = dma_fence_wait_timeout(fence, false, tmo);
> -	dma_fence_put(fence);
> -
> -	if (r < 0 || tmo <= 0) {
> -		dev_err(adev->dev, "recover vram bo from shadow failed, r is %ld, tmo is %ld\n", r, tmo);
> -		return -EIO;
> -	}
> -
> -	dev_info(adev->dev, "recover vram bo from shadow done\n");
> -	return 0;
> -}
> -
> -
>   /**
>    * amdgpu_device_reset_sriov - reset ASIC for SR-IOV vf
>    *
> @@ -5116,12 +5039,8 @@ static int amdgpu_device_reset_sriov(struct amdgpu_device *adev,
>   	if (r)
>   		return r;
>   
> -	if (adev->virt.gim_feature & AMDGIM_FEATURE_GIM_FLR_VRAMLOST) {
> +	if (adev->virt.gim_feature & AMDGIM_FEATURE_GIM_FLR_VRAMLOST)
>   		amdgpu_inc_vram_lost(adev);
> -		r = amdgpu_device_recover_vram(adev);
> -	}
> -	if (r)
> -		return r;
>   
>   	/* need to be called during full access so we can't do it later like
>   	 * bare-metal does.
> @@ -5541,9 +5460,7 @@ int amdgpu_do_asic_reset(struct list_head *device_list_handle,
>   			}
>   		}
>   
> -		if (!r)
> -			r = amdgpu_device_recover_vram(tmp_adev);
> -		else
> +		if (r)
>   			tmp_adev->asic_reset_res = r;
>   	}
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index e32161f6b67a3..a987f671b1d53 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -77,24 +77,6 @@ static void amdgpu_bo_user_destroy(struct ttm_buffer_object *tbo)
>   	amdgpu_bo_destroy(tbo);
>   }
>   
> -static void amdgpu_bo_vm_destroy(struct ttm_buffer_object *tbo)
> -{
> -	struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
> -	struct amdgpu_bo *shadow_bo = ttm_to_amdgpu_bo(tbo), *bo;
> -	struct amdgpu_bo_vm *vmbo;
> -
> -	bo = shadow_bo->parent;
> -	vmbo = to_amdgpu_bo_vm(bo);
> -	/* in case amdgpu_device_recover_vram got NULL of bo->parent */
> -	if (!list_empty(&vmbo->shadow_list)) {
> -		mutex_lock(&adev->shadow_list_lock);
> -		list_del_init(&vmbo->shadow_list);
> -		mutex_unlock(&adev->shadow_list_lock);
> -	}
> -
> -	amdgpu_bo_destroy(tbo);
> -}
> -
>   /**
>    * amdgpu_bo_is_amdgpu_bo - check if the buffer object is an &amdgpu_bo
>    * @bo: buffer object to be checked
> @@ -108,8 +90,7 @@ static void amdgpu_bo_vm_destroy(struct ttm_buffer_object *tbo)
>   bool amdgpu_bo_is_amdgpu_bo(struct ttm_buffer_object *bo)
>   {
>   	if (bo->destroy == &amdgpu_bo_destroy ||
> -	    bo->destroy == &amdgpu_bo_user_destroy ||
> -	    bo->destroy == &amdgpu_bo_vm_destroy)
> +	    bo->destroy == &amdgpu_bo_user_destroy)
>   		return true;
>   
>   	return false;
> @@ -722,52 +703,6 @@ int amdgpu_bo_create_vm(struct amdgpu_device *adev,
>   	return r;
>   }
>   
> -/**
> - * amdgpu_bo_add_to_shadow_list - add a BO to the shadow list
> - *
> - * @vmbo: BO that will be inserted into the shadow list
> - *
> - * Insert a BO to the shadow list.
> - */
> -void amdgpu_bo_add_to_shadow_list(struct amdgpu_bo_vm *vmbo)
> -{
> -	struct amdgpu_device *adev = amdgpu_ttm_adev(vmbo->bo.tbo.bdev);
> -
> -	mutex_lock(&adev->shadow_list_lock);
> -	list_add_tail(&vmbo->shadow_list, &adev->shadow_list);
> -	vmbo->shadow->parent = amdgpu_bo_ref(&vmbo->bo);
> -	vmbo->shadow->tbo.destroy = &amdgpu_bo_vm_destroy;
> -	mutex_unlock(&adev->shadow_list_lock);
> -}
> -
> -/**
> - * amdgpu_bo_restore_shadow - restore an &amdgpu_bo shadow
> - *
> - * @shadow: &amdgpu_bo shadow to be restored
> - * @fence: dma_fence associated with the operation
> - *
> - * Copies a buffer object's shadow content back to the object.
> - * This is used for recovering a buffer from its shadow in case of a gpu
> - * reset where vram context may be lost.
> - *
> - * Returns:
> - * 0 for success or a negative error code on failure.
> - */
> -int amdgpu_bo_restore_shadow(struct amdgpu_bo *shadow, struct dma_fence **fence)
> -
> -{
> -	struct amdgpu_device *adev = amdgpu_ttm_adev(shadow->tbo.bdev);
> -	struct amdgpu_ring *ring = adev->mman.buffer_funcs_ring;
> -	uint64_t shadow_addr, parent_addr;
> -
> -	shadow_addr = amdgpu_bo_gpu_offset(shadow);
> -	parent_addr = amdgpu_bo_gpu_offset(shadow->parent);
> -
> -	return amdgpu_copy_buffer(ring, shadow_addr, parent_addr,
> -				  amdgpu_bo_size(shadow), NULL, fence,
> -				  true, false, 0);
> -}
> -
>   /**
>    * amdgpu_bo_kmap - map an &amdgpu_bo buffer object
>    * @bo: &amdgpu_bo buffer object to be mapped
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> index bc42ccbde659a..a4fa1f296daec 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> @@ -130,8 +130,6 @@ struct amdgpu_bo_user {
>   
>   struct amdgpu_bo_vm {
>   	struct amdgpu_bo		bo;
> -	struct amdgpu_bo		*shadow;
> -	struct list_head		shadow_list;
>   	struct amdgpu_vm_bo_base        entries[];
>   };
>   
> @@ -269,22 +267,6 @@ static inline bool amdgpu_bo_encrypted(struct amdgpu_bo *bo)
>   	return bo->flags & AMDGPU_GEM_CREATE_ENCRYPTED;
>   }
>   
> -/**
> - * amdgpu_bo_shadowed - check if the BO is shadowed
> - *
> - * @bo: BO to be tested.
> - *
> - * Returns:
> - * NULL if not shadowed or else return a BO pointer.
> - */
> -static inline struct amdgpu_bo *amdgpu_bo_shadowed(struct amdgpu_bo *bo)
> -{
> -	if (bo->tbo.type == ttm_bo_type_kernel)
> -		return to_amdgpu_bo_vm(bo)->shadow;
> -
> -	return NULL;
> -}
> -
>   bool amdgpu_bo_is_amdgpu_bo(struct ttm_buffer_object *bo);
>   void amdgpu_bo_placement_from_domain(struct amdgpu_bo *abo, u32 domain);
>   
> @@ -343,9 +325,6 @@ u64 amdgpu_bo_gpu_offset(struct amdgpu_bo *bo);
>   u64 amdgpu_bo_gpu_offset_no_check(struct amdgpu_bo *bo);
>   void amdgpu_bo_get_memory(struct amdgpu_bo *bo,
>   			  struct amdgpu_mem_stats *stats);
> -void amdgpu_bo_add_to_shadow_list(struct amdgpu_bo_vm *vmbo);
> -int amdgpu_bo_restore_shadow(struct amdgpu_bo *shadow,
> -			     struct dma_fence **fence);
>   uint32_t amdgpu_bo_get_preferred_domain(struct amdgpu_device *adev,
>   					    uint32_t domain);
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index a060c28f0877c..8cda1d02dade3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -465,7 +465,6 @@ int amdgpu_vm_validate(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   {
>   	uint64_t new_vm_generation = amdgpu_vm_generation(adev, vm);
>   	struct amdgpu_vm_bo_base *bo_base;
> -	struct amdgpu_bo *shadow;
>   	struct amdgpu_bo *bo;
>   	int r;
>   
> @@ -486,16 +485,10 @@ int amdgpu_vm_validate(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   		spin_unlock(&vm->status_lock);
>   
>   		bo = bo_base->bo;
> -		shadow = amdgpu_bo_shadowed(bo);
>   
>   		r = validate(param, bo);
>   		if (r)
>   			return r;
> -		if (shadow) {
> -			r = validate(param, shadow);
> -			if (r)
> -				return r;
> -		}
>   
>   		if (bo->tbo.type != ttm_bo_type_kernel) {
>   			amdgpu_vm_bo_moved(bo_base);
> @@ -2123,10 +2116,6 @@ void amdgpu_vm_bo_invalidate(struct amdgpu_device *adev,
>   {
>   	struct amdgpu_vm_bo_base *bo_base;
>   
> -	/* shadow bo doesn't have bo base, its validation needs its parent */
> -	if (bo->parent && (amdgpu_bo_shadowed(bo->parent) == bo))
> -		bo = bo->parent;
> -
>   	for (bo_base = bo->vm_bo; bo_base; bo_base = bo_base->next) {
>   		struct amdgpu_vm *vm = bo_base->vm;
>   
> @@ -2454,7 +2443,6 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   	root_bo = amdgpu_bo_ref(&root->bo);
>   	r = amdgpu_bo_reserve(root_bo, true);
>   	if (r) {
> -		amdgpu_bo_unref(&root->shadow);
>   		amdgpu_bo_unref(&root_bo);
>   		goto error_free_delayed;
>   	}
> @@ -2546,11 +2534,6 @@ int amdgpu_vm_make_compute(struct amdgpu_device *adev, struct amdgpu_vm *vm)
>   	vm->last_update = dma_fence_get_stub();
>   	vm->is_compute_context = true;
>   
> -	/* Free the shadow bo for compute VM */
> -	amdgpu_bo_unref(&to_amdgpu_bo_vm(vm->root.bo)->shadow);
> -
> -	goto unreserve_bo;
> -
>   unreserve_bo:
>   	amdgpu_bo_unreserve(vm->root.bo);
>   	return r;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> index e39d6e7643bfb..c8e0b8cfd3363 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
> @@ -383,14 +383,6 @@ int amdgpu_vm_pt_clear(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   	if (r)
>   		return r;
>   
> -	if (vmbo->shadow) {
> -		struct amdgpu_bo *shadow = vmbo->shadow;
> -
> -		r = ttm_bo_validate(&shadow->tbo, &shadow->placement, &ctx);
> -		if (r)
> -			return r;
> -	}
> -
>   	if (!drm_dev_enter(adev_to_drm(adev), &idx))
>   		return -ENODEV;
>   
> @@ -448,10 +440,7 @@ int amdgpu_vm_pt_create(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   			int32_t xcp_id)
>   {
>   	struct amdgpu_bo_param bp;
> -	struct amdgpu_bo *bo;
> -	struct dma_resv *resv;
>   	unsigned int num_entries;
> -	int r;
>   
>   	memset(&bp, 0, sizeof(bp));
>   
> @@ -484,42 +473,7 @@ int amdgpu_vm_pt_create(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   	if (vm->root.bo)
>   		bp.resv = vm->root.bo->tbo.base.resv;
>   
> -	r = amdgpu_bo_create_vm(adev, &bp, vmbo);
> -	if (r)
> -		return r;
> -
> -	bo = &(*vmbo)->bo;
> -	if (vm->is_compute_context || (adev->flags & AMD_IS_APU)) {
> -		(*vmbo)->shadow = NULL;
> -		return 0;
> -	}
> -
> -	if (!bp.resv)
> -		WARN_ON(dma_resv_lock(bo->tbo.base.resv,
> -				      NULL));
> -	resv = bp.resv;
> -	memset(&bp, 0, sizeof(bp));
> -	bp.size = amdgpu_vm_pt_size(adev, level);
> -	bp.domain = AMDGPU_GEM_DOMAIN_GTT;
> -	bp.flags = AMDGPU_GEM_CREATE_CPU_GTT_USWC;
> -	bp.type = ttm_bo_type_kernel;
> -	bp.resv = bo->tbo.base.resv;
> -	bp.bo_ptr_size = sizeof(struct amdgpu_bo);
> -	bp.xcp_id_plus1 = xcp_id + 1;
> -
> -	r = amdgpu_bo_create(adev, &bp, &(*vmbo)->shadow);
> -
> -	if (!resv)
> -		dma_resv_unlock(bo->tbo.base.resv);
> -
> -	if (r) {
> -		amdgpu_bo_unref(&bo);
> -		return r;
> -	}
> -
> -	amdgpu_bo_add_to_shadow_list(*vmbo);
> -
> -	return 0;
> +	return amdgpu_bo_create_vm(adev, &bp, vmbo);
>   }
>   
>   /**
> @@ -569,7 +523,6 @@ static int amdgpu_vm_pt_alloc(struct amdgpu_device *adev,
>   	return 0;
>   
>   error_free_pt:
> -	amdgpu_bo_unref(&pt->shadow);
>   	amdgpu_bo_unref(&pt_bo);
>   	return r;
>   }
> @@ -581,17 +534,10 @@ static int amdgpu_vm_pt_alloc(struct amdgpu_device *adev,
>    */
>   static void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry)
>   {
> -	struct amdgpu_bo *shadow;
> -
>   	if (!entry->bo)
>   		return;
>   
>   	entry->bo->vm_bo = NULL;
> -	shadow = amdgpu_bo_shadowed(entry->bo);
> -	if (shadow) {
> -		ttm_bo_set_bulk_move(&shadow->tbo, NULL);
> -		amdgpu_bo_unref(&shadow);
> -	}
>   	ttm_bo_set_bulk_move(&entry->bo->tbo, NULL);
>   
>   	spin_lock(&entry->vm->status_lock);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> index 9b748d7058b5c..390432a22ddd5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_sdma.c
> @@ -35,16 +35,7 @@
>    */
>   static int amdgpu_vm_sdma_map_table(struct amdgpu_bo_vm *table)
>   {
> -	int r;
> -
> -	r = amdgpu_ttm_alloc_gart(&table->bo.tbo);
> -	if (r)
> -		return r;
> -
> -	if (table->shadow)
> -		r = amdgpu_ttm_alloc_gart(&table->shadow->tbo);
> -
> -	return r;
> +	return amdgpu_ttm_alloc_gart(&table->bo.tbo);
>   }
>   
>   /* Allocate a new job for @count PTE updates */
> @@ -273,17 +264,13 @@ static int amdgpu_vm_sdma_update(struct amdgpu_vm_update_params *p,
>   
>   		if (!p->pages_addr) {
>   			/* set page commands needed */
> -			if (vmbo->shadow)
> -				amdgpu_vm_sdma_set_ptes(p, vmbo->shadow, pe, addr,
> -							count, incr, flags);
>   			amdgpu_vm_sdma_set_ptes(p, bo, pe, addr, count,
>   						incr, flags);
>   			return 0;
>   		}
>   
>   		/* copy commands needed */
> -		ndw -= p->adev->vm_manager.vm_pte_funcs->copy_pte_num_dw *
> -			(vmbo->shadow ? 2 : 1);
> +		ndw -= p->adev->vm_manager.vm_pte_funcs->copy_pte_num_dw;
>   
>   		/* for padding */
>   		ndw -= 7;
> @@ -298,8 +285,6 @@ static int amdgpu_vm_sdma_update(struct amdgpu_vm_update_params *p,
>   			pte[i] |= flags;
>   		}
>   
> -		if (vmbo->shadow)
> -			amdgpu_vm_sdma_copy_ptes(p, vmbo->shadow, pe, nptes);
>   		amdgpu_vm_sdma_copy_ptes(p, bo, pe, nptes);
>   
>   		pe += nptes * 8;

Re: [PATCH AUTOSEL 6.11 72/76] drm/amdgpu: nuke the VM PD/PT shadow handling

[Sasha Levin]

On Tue, Oct 08, 2024 at 08:46:01AM +0200, Christian König wrote:
>Hi Sasha,
>
>Am 04.10.24 um 20:17 schrieb Sasha Levin:
>>From: Christian König <christian.koenig@amd.com>
>>
>>[ Upstream commit 7181faaa4703705939580abffaf9cb5d6b50dbb7 ]
>>
>>This was only used as workaround for recovering the page tables after
>>VRAM was lost and is no longer necessary after the function
>>amdgpu_vm_bo_reset_state_machine() started to do the same.
>>
>>Compute never used shadows either, so the only proplematic case left is
>>SVM and that is most likely not recoverable in any way when VRAM is
>>lost.
>
>why is that backported to older kernels? It's basically just removing 
>an old and now unused feature.
>
>Lijo pointed out a related bug fixed by removing the feature, but that 
>only happens extremely rarely and in my view doesn't really justify a 
>backport.

I'll drop it then, thanks!

-- 
Thanks,
Sasha